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Rules Design 2 - Metric Time and Distance

In the first chapter we examined miles per hour and looked at ways to convert these into inches on the wargame table. In this section we will look at kilometers per hour.

The following table shows kilometers per hour and the actual meters per hour and meters per minute that may be moved. The column at the end rounds up the meters per minute to drop all fractions and have easier numbers to work with. While some may prefer multiples of the prime number 17 for esoteric reasons, multiples of 18 are divisible by 2, 3, 6 and 9. (The rounded value at 1 kph actually equals 1.077984 kph. At 30 kph it equals 32.393521 kph, so the distortion is already about 8% at this speed.)

 

Kilometers per hour

Meters per hour

Meters per minute

Rounded

1

1000

17

18

2

2000

33

36

3

3000

50

54

4

4000

67

72

5

5000

83

90

10

10,000

167

180

15

15,000

250

270

20

20,000

333

360

25

25,000

417

450

30

30,000

500

540

With this information it is very easy to relate time to distance moved. We will use the rounded numbers from the table above. In 1 minute, a unit with a movement rate of 1 kilometer per hour can move 18 meters. A unit with a movement rate of 3 kilometers per hour can move 54 meters.

We now have another practical and realistic time to movement relationship. How do we use these numbers on a wargame table? If a centimeter equals 1 meter in your wargame rules (1/100 scale), a unit that can move at a rate of 3 kilometers per hour (54 meters per turn) can move 54 centimeters in one turn. (Keep in mind that we are working with a 1 minute time frame.)

1 minute turn

Kilometers per hour

Centimeters of movement,

if 1 cm equals 1 meter

1

18

2

36

3

54

4

72

5

90

10

180

15

270

20

360

25

450

30

540

Probably very few rules use a scale of 1 centimeter equals 1 meter, so we will want to be able to change the scale. We will also want to be able to change the amount of time per turn. This is a relatively straightforward process and a few examples will illustrate this:

5 minute turn

10 minute turn

Kilometers per hour

Centimeters moved, if 1 cm equals 2 meters

Centimeters moved, if 1 cm equals 5 meters

Centimeters moved, if 1 cm equals 2 meters

Centimeters moved, if 1 cm equals 5 meters

1

45

18

90

36

2

90

36

180

72

3

135

54

270

108

4

180

72

360

144

5

225

90

450

180

 

1 minute turn

5 minute turn

10 minute turn

15 minute turn

Kilometers per hour

Centimeters moved, if 1 centimeter equals 1 meter

1

18

90

180

270

2

36

180

360

450

3

54

270

540

810

4

72

360

720

1080

5

90

450

900

1350

In the same manner that we converted yards and miles per hour we can create a time and distance scale where a unit can move one centimeter per turn for every kilometer per hour of its movement rate. The following table provides the details for a number of different scales.

If the scale is:

It takes this amount of seconds to move the distance at 1 kph

1 centimeter = 35 centimeters [1/35]

1.26

1 centimeter = 48 centimeters [1/48]

1.73

1 centimeter = 72 centimeters [1/72]

2.59

1 centimeter = 86 centimeters [1/86]

3.10

1 centimeter = 1 meter [1/100]

3.60

1 centimeter = 1.44 meters [1/144]

5.18

1 centimeter = 2.85 meters [1/285]

10.26

1 centimeter = 5 meters [1/500]

18.00

1 centimeter = 7 meters [1/700]

25.20

1 centimeter = 10 meters [1/1000]

36.00

Based on the above table, if a wargamer using 1/285 scale vehicles sets the length of the turn at 10 seconds (15.26 rounded down) a tank with a speed of 40 kph will be able to move 40 centimeters per turn. Keep in mind that terrain has not been factored in, so these are maximum speeds.

Comparing miles and kilometers

At some point a wargame designer may want to compare the movement rates of miles per hour with those of kilometers per hour. This might be particularly true in the post-World War Two era, when the speeds of American tanks are usually given in miles per hour and those of European nations are given in kilometers per hour. How far does a tank with a cross country speed of 20 miles per hour move in terms of kilometers per hour?

The following table provides the corresponding kilometers per hour, meters per hour and meters per minute for various speeds in miles per hour. The column at the end rounds up the meters per minute to drop all fractions and have easier numbers to work with. (The rounded value at 1 mph actually equals 1.0683654 mph. At 30 mph it equals 30.2050963 mph, less than a quarter of a mph over our rounded number, so the distortion is not too great.)

Miles per hour

Kilometers per hour

Meters per hour

Meters per minute

Rounded up

1

1.609

1609.00

26.82

27

2

3.218

3218.00

53.63

54

3

4.827

4827.00

80.45

81

4

6.436

6436.00

107.27

108

5

8.045

8045.00

134.08

135

10

16.09

16090.00

268.17

270

15

24.135

24135.00

402.25

405

20

32.18

32180.00

536.33

540

25

40.225

40225.00

670.42

675

30

48.27

48270.00

804.50

810

The following table provides the corresponding miles per hour, yards per hour and yards per minute for various speeds in kilometers per hour. The column at the end rounds down the yards per minute to drop all fractions and have easier numbers to work with. (The rounded value at 1 kph actually equals 0.98973607 kph. At 30 kph it equals 29.6920821 kph, less than a third of a kph under our rounded number, so the distortion is not too great.)

Kilometers per hour

Miles per hour

Yards per hour

Yards per minute

Rounded down

1

0.62

1091.20

18.19

18

2

1.243

2187.68

36.46

36

3

1.864

3280.64

54.68

54

4

2.486

4375.36

72.92

72

5

3.107

5468.32

91.14

90

10

6.214

10936.64

182.28

180

15

9.321

16404.96

273.42

405

20

12.428

21873.28

364.55

360

25

15.535

27341.60

455.69

450

30

18.642

32809.92

546.83

540

 

 

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